From the releases:
The Zeus panzermech was built to operate as a tank hunter in difficult terrain or to assist the Thor panzermechs in reaching their urban targets. Unsuited to the urban role, once the Thors were delivered to the target, the Zeus often protected the flanks of an assault, preventing enemy armour from cutting off the attacking forces’ lines of supply.
Having suffered terribly at the hands of German Thor and Zeus heavy panzermechs, the Soviets put a tremendous effort into replicating their effect. After capturing a Thor, they were able to replicate much of the multi-leg technology.